Partners and International Organizations
(English)
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AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GR, HR, IE, IL, IT, LT, LU, LV, MK, NL, NO, PL, PT, RO, RS, SE, SI, TR, UK
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Abstract
(English)
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Xenobiotics with endocrine disrupting potential represent a potential risk to the environment. This study evaluated the potential to stimulate the targeted removal of such xenobiotics through bioaugmentation of membrane bioreactors (MBR). Here, the fate of bisphenol A (BPA), a representative endocrine disrupting chemical (EDC), was studied in MBR-Systems. Bioaugmentation - the introduction of microbial strains bearing a desired biodegradation potential into a contaminated environment - was operated here through successive additions of Sphingomonas sp. strain TTNP3, a microorganism able to degrade BPA to MBR-systems. In order to evaluate the efficiency of the bioaugmentation process, methods for the detection of BPA and metabolites thereof (using 14C-labelled-BPA) and for the detection of the bioaugmented species (using molecular biological methods) were develop. These methods were applied to accurately monitor the fate of BPA, and evaluate the persistence of the species introduced in the reactor. It was demonstrated that bioaugmentation significantly influenced the fate of BPA in MBRs. While most of the radioactivity was retained in the retentate of the non augmented control reactor, large proportions of radioactivity were retrieved in the effluent of the bioaugmented reactor (84% versus 25% after 5 days). This apparent difference can be explained by the metabolism of BPA by S. TTNP3, since HPLC-DAD/LSC, HPLC-MSn and GC-MS analyses revealed that the bio-augmented reactor produced polar metabolites, whereas the control reactor effluent contained >98% BPA. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and specific cell activity tests indicated that this difference in the reactor performance was due to the presence and persistence of the strain TTNP3 in the bioaugmented lab-scale membrane bioreactor. In order to evaluate the applicability of bioaugmentation in larger scale, Sphingomonas sp. strain TTNP3 was cultivated in large scale and bioaugmented to a pilot reactor. The results obtained at lab-scale suggest that bioaugmentation in MBRs can enhance the biodegradation of BPA und therefore its removal process. Bioaugmentation might be an efficient manner to enhance xenobiotic removal during wastewater treatment. Due to unforeseen experimental problems, a confirmation of the lab scale results was not achieved during the pilot experiment.
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